Other Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Accounts receivable	$ 4,286		$ 4,208
Corporate/bank owned life insurance	4,260		4,216
Equity in joint ventures and other investments	2,748	[1]	2,677	[1]
Income taxes receivable	2,681		2,573
Fails to deliver	1,277		961
Fair value of hedging derivatives	1,232		1,600
Software	1,046		986
Prepaid expenses	605		784
Due from customers on acceptances	355		321
Prepaid pension assets	176		144
Other	1,089		1,369
Total other assets	$ 19,755		$ 19,839

[1] Includes Federal Reserve Bank stock of $434 million and $429 million, respectively, at cost.